Method for separating an organic phase from an electrolyte-containing aqueous and organic phase

ABSTRACT

A method for separating electrolyte-containing water from an organic phase by means of permeation on a hydrophobic separating means. The permeated organic solution is substantially depleted in water and the retained water is enriched with electrolytes.

This is a Division of application Ser. No. 11/876,094, filed Oct. 22,2007, now allowed, which claims priority of German application SerialNo. 10 2006 050 381.3, filed Oct. 25, 2006.

The invention relates to a novel method for separating anelectrolyte-free organic phase from a mixture of electrolyte-containing(salt-containing) aqueous and organic phases. The electrolyte-containingwater is dispersed or emulsified in the organic phase.

BACKGROUND OF THE INVENTION

The separation of electrolytes (salts, alkalis, acids) and water fromorganic phases, for example water-immiscible polymers, aromatics,aliphatics, plays an important role in industrial processes. Accordingto the prior art, such separation has been carried out by means ofcentrifuging, deposition, distillation, spray drying,evaporation-extrusion, precipitation and/or fiber coalescence. Ingeneral, the separation of the electrolytes (alkali and acid) is notcarried out until after neutralization to form the corresponding salts,with acids and alkalis.

A disadvantage is the consumption of neutralizing agents and theconcomitant loss of alkali and/or acid, as well as disposal/use of thesalt. Other disadvantages of the methods described above for separatingan electrolyte-free (alkali, acid, salt) organic phase are that theynecessitate on the one hand extensive use of energy in order to separatethe water and, on the other hand, elaborate separation of residualcontents of electrolytes (salts) by washing processes. This entails highcosts owing to the associated water treatment and the high energydemand. Tests to improve the phase separation, for example temperaturevariation, improved centrifuges or reducing the size of the separatorsby using coalescence aids, often lead to insufficient separation or astrong susceptibility to clogging of the coalescence aids by build-up ofsalt.

In the specific case of the polyether polyol production process, thesalts and residual water contents are separated from the polyol phaseaccording to the prior art by centrifuging, deposition or distillationand filtration (see, for example EP 0 038 986 A2).

On an industrial scale, polyether polyols are usually produced byaddition of alkylene oxides, in particular polypropylene oxide and/orethylene oxide, to starting compounds with acidic hydrogen atoms (forexample water, polyalkylenes or polyamines) in the presence of basicsubstances, generally alkali metal hydroxides such as KOH or NaOH, as acatalyst. In one of the processing methods which is customary atpresent, the basic catalyst (for example KOH) is removed from thealkaline polymerizate in a plurality of method steps. First, thealkaline polymerizate is neutralized e.g. with dilute sulfuric acid,after which the majority of water is distilled off with simultaneouscrystallization of the inorganic salt (here K₂SO₄). The precipitatedsalt is filtered off, whereupon the residual water is distilled off andthe residual amount of salt is removed by filtration.

The disadvantages of these known neutralization methods are, on the onehand, the consumption of neutralization acid and very high energyconsumption for distilling the water. On the other hand, it is difficultto filter off the usually very finely divided salt.

The polyether polyol mixture obtained after the polymerization consistsof an organic phase, which contains polyether polyol and the by-productscreated during the reaction (inter alia 1,4-dioxane,2,5-dimethyl-1,4-dioxane, 2,4-dimethyl-1,3-dioxalane,2-ethyl-4-methyl-1,3-dioxalane, 2-methyl-2-pentanal, acetaldehyde,acetone, allyl alcohol, allyloxipropanol, DPG allyl ether, ethylbenzene,ethylene, ethylene oxide, methanol, propionaldehyde, propylene oxideand/or toluene). Water is dissolved in this phase, the extent of whichdepends on the type of polyether polyol, i.e. the molecular weight or Cchain length and the proportion and distribution of ethylene oxide andpropylene oxide. The aqueous phase contains salt, which may contain ionsof the alkali and alkaline-earth metal group, for example Li, Na, K, Be,Mg, Ca, Sr, Ba and creates for example H₂SO₄, HCl, H₃PO₄, HNO₃ or CO₂during the treatment or neutralization with acids. A water-immisciblearomatic or aliphatic solvent (for example toluene or hexane) mayfurthermore be used in order to improve the phase separation.

In the specific case of producing polycarbonate, copolycarbonate orpolyester carbonate according to the so-called phase interface method(cf. phase interface method for polycarbonate production, see Ullmann'sEncyclopedia of Industrial Chemistry 2002 Wiley-VCH Verlag),dihydroxyarylalkanes in the form of their alkali metal salts are reactedwith phosgene in the heterogeneous presence of inorganic bases such assodium hydroxide or an inorganic solvent (for example chlorobenzeneand/or methylene chloride), in which the polycarbonate product is highlysoluble. During the reaction, the aqueous phase is distributed in theorganic phase and after the reaction, the organic phase containingpolycarbonate is washed with an aqueous liquid and neutralized withacids (for example HCl), so that inter alia electrolytes (for examplesodium chloride, sodium carbonate, optionally sodium sulphate) andtraces of unreacted raw materials (for example phenol, isooctylphenol,ethyl piperidine and bisphenol) are removed, and the washing liquid issubsequently separated. The aqueous phase is conventionally separated byspray drying, evaporation-extrusion, precipitation of the polycarbonate,centrifuging (see EP 264 885 A2) or by fiber coalescence (see DE 19 510061 A1).

In general, salts constitute contamination and must be separated fromthe organic product (for example polycarbonate or polyether polyol).

The object can be achieved by a novel filtration method in which bothwater and electrolytes (alkalis, acids, salts) are retained, and onlythe organic phase optionally with residues of physically dissolved wateris let through organophilic filters.

Filtration methods are conventionally used for solid-liquid separation,for example to separate particles. They have the disadvantage that theyare not capable of separating finely distributed dispersions oremulsions of water and salt in organic solvents (products) from oneanother. Conventional membrane filtration methods by means of polymermembranes (for example of polyether sulfone, polysulfone, polyamide,cellulose acetate) generally separate the aqueous phase from theorganic-aqueous mixture, so that the filtered aqueous phase contains theelectrolytes and is generally the desired product, and the organic phaseoften contains residual electrolytes and must therefore be treatedseparately or is disposed of. They furthermore have the disadvantage oflow chemical stability with respect to organic compounds and a hightemperature sensitivity.

Another way of separating the phases from one another is to usemembranes which separate water selectively (see Verfahren zurPervaporation oder Dampfpermeation; see Melin,Rautenbach—Membranverfahren—Springer Verlag 2004). In this case, theaqueous phase penetrates through the membrane and the organic phase isretained. In the case of salt-containing solutions, precipitation of thesalts takes place in the region of the separating and support layers ofthese membranes, so that these membranes are susceptible to clogging. Atthe same time, these membranes exhibit a low permeation flux.

Feng et al. have furthermore described the use of superhydrophobiccoated sieves for separating diesel oil and water. (Feng, L., Zhang, Z.,Mai, Z., Ma, Y., Liu, B., Jiang, L. & Zhu, D., A Super-Hydrophobic andSuper-Oleophilic Coating Mesh Film for the Separation of Oil and Water.Angewandte Chemie, 116 (2004) 2046). Besides production of thesuperhydrophobic coated sieves, Feng et al. describe the influence ofthe sieve mesh width on the hydrophobicity of the sieve. Thesuperhydrophobicity is described with the aid of water drops and dieseloil drops. The separation of diesel oil-water is described as a possiblefield of use, the liquids being, however, explicitly described asnon-emulsified. The work by Feng relates exclusively to the productionof the superhydrophobic sieve for separating water and diesel oil. Theseparation of salt-containing or electrolyte-containing aqueous phasesis not described and carried out.

It is therefore an object of the present invention to enable or improvethe separation of an electrolyte-free organic phase from anelectrolyte-containing (salt-containing) aqueous and organic phase.

SUMMARY OF THE INVENTION

It has now been found that this object can be achieved by the specialseparation method described below. This is substantially a method ofseparation via a separating means comprising hydrophobic orhydrophobicized material, which may be formed as a membrane or mesh, bymeans of which the aqueous phase and electrolytes (salts, alkalis,acids) can be retained while the organic phase permeates through thematerial (membrane, mesh). Substantial separation of theelectrolyte-containing aqueous phase from the organic phase can therebybe achieved.

DETAILED DESCRIPTION

The invention provides a method for separating an organic phase from amixture of an organic phase comprising an organic solution and anaqueous phase comprising an electrolyte-containing water, characterisedin that the mixture to be separated is passed over a hydrophobic porousseparating means, in particular an organophilic membrane or a flattextile structure or a perforated plate, in particular a flat textilestructure of metal or plastic which either is inherently hydrophobic orwhich has a hydrophobic coating or hydrophobic surface, at least a partof the organic phase of the mixture permeating through the separatingmeans while the electrolyte-containing aqueous phase is retained fullyor to a large part together with the remainder, if any, of the organicphase.

An organophilic (hydrophobic) separating means in the context of theinvention comprises a separating means having a surface which has awater contact angle in air of >90° under standard conditions oftemperature and pressure.

The separating means is preferably an organophilic membrane of ceramic,metal, polymer, glass or composite materials of ceramic and glass and/orpolymer and ceramic, which either has a coating of organophilicmaterial, for example perfluoro polymers (polytetrafluoroethylene(PTFE), polyvinylidene fluoride (PVDF)), hydrophobic polymers (forexample polypropylene PP, poly(methylsilsesquioxan) PMSSQ) or a coatingformed from reactive materials such as isocyanates, silanes or hybridcopolymers.

The organophilic membrane particularly preferably is formed of ceramic,metal, polymer, glass or corresponding composite materials of ceramicand glass or of polymer and ceramic or metal, which has a sufficienthydrophobicity (or organophilicity) without further modification (e.g.coating).

A particularly preferred method is characterised in that theorganophilic membrane is a hydrophobicized ceramic membrane.

In particular, membranes formed from base materials such as Al₂O₃, ZrO₂,TiO₂, SiC (silicon carbide) or combinations of these compounds are usedas ceramic membranes.

The organophilic ceramic membrane has in particular a pore width of from0.05 μm to 10 μm, particularly preferably from 0.1 μm to 5 μm.

Electrolytes in the context of the invention are salts, alkalis oracids, in particular inorganic compounds, dissolved in water.

A particularly preferred method/separating means is characterised inthat the hydrophobic porous membrane is an organophilic polymermembrane. In particular, membranes formed of polymers selected from thegroup consisting of (PP polypropylene), (PVDF polyvinylidene fluoride),(PTFE polytetrafluoroethylene), silicones and combinations of suchpolymers are used as organophilic polymer membranes.

The organophilic polymer membrane has pores with in particular a porewidth of from 0.05 μm to 10 μm, particularly preferably from 0.1 μm to 5μm.

An alternative preferred method is characterised in that a woven metalmesh with a hydrophobic coating is used as the hydrophobic porousseparating means, the metal mesh preferably having a mesh width <500 μm,more preferably <50 μm, most preferably <5 μm.

A suitable organophilic material particularly preferred for ahydrophobic coating is selected from a list of the following materialsbut not in principle restricted thereto: PTFE (for example Teflon® AF,available from DuPont), PTFE dispersion, isocyanates, organic and/orfluoro polymers or latex, hybrid copolymers, fatty acids, silanes,lacquers, silicones, silicone oils or polysilsesquioxans, or organicand/or fluoro deposits applied from a plasma process, or a mixture ofdifferent aforementioned coating agents. The hybrid copolymers are inparticular diblock copolymers containing one hydrophobic polymer blockwhich binds readily to the metal mesh and one hydrophobic polymer blockwhich does not bind to the metal mesh, wherein a preferred variant ofthe binding block consists of a polysilsesquioxan, and particularlypreferably poly(methylsilsesquioxan) or poly(stearylsilsesquioxan) and aparticularly preferred variant of the non-binding hydrophobic polymerblock can be selected from, but is not limited to, the group comprisingpolystyrene, polymethyl acrylate, polyethyl hexyl acrylate, polymethylmethacrylate and polydecyl methacrylate.

A particularly preferred method is characterised in that a hydrophobicflat textile structure, in particular a woven, knitted fabric, felt ofhydrophobic plastic (in particular polypropylene, PTFE or PVDF) withoutfurther modification is used as the hydrophobic porous separating means.The hydrophobic flat textile structure preferably has a pore/mesh width<500 μm, more preferably <50 μm, most preferably <5 μm.

In a more particularly preferred method, the hydrophobic coating isproduced by applying a smooth hydrophobic coating onto a previouslyroughened surface of the separating means.

The method is preferably employed when the mixture to be separated is anemulsion or dispersion comprised of water, electrolyte and organics, inparticular electrolytes of the alkali and/or alkaline-earth metals, andorganics of polymers, aromatics and/or aliphatics.

The method is particularly preferably employed when the mixture to beseparated is an emulsion or dispersion of an organic phase comprisingpolycarbonate dissolved in organic solvent, and an aqueous phasecomprising water and optionally including salts of the alkali andalkaline-earth metals, in particular sodium, potassium, magnesium and/orcalcium.

The method is also preferably employed when the mixture to be separatedis an organic phase comprising a mixture of a polyol, optionally in asolvent such as an aromatic or aliphatic hydrocarbons for exampletoluene or hexane, and an aqueous phase comprising water and a salt ofthe alkali and alkaline-earth metals, such as sodium, potassium,magnesium or calcium.

The hydrophobic separating means in the method according to theinvention is characterized by a high separation rate of salt and waterfrom the organic mixture, together with a high permeation flux and ahigh stability with respect to organic solvents.

Salts contained in the mixture to be separated are mostly retainedtogether with the aqueous phase and can then readily be removed.

A hydrophobicized mesh particularly preferably is one formed of a shape-and pressure-stable stainless steel, particularly preferably of a shape-and pressure-stable austenitic stainless steels (1.4404, 1.4571). Themesh is preferably to be employed with a mesh width <500 μm, morepreferably with a mesh width <100 μm, particularly preferably with amesh width 20 μm and most preferably with a mesh width <5 μm.

The coating of the mesh preferably is formed of a hydrophobic material,more preferably of nonpolar polymers, hybrid copolymers,polysilsesquioxans or silanes, particularly preferably ofpolysilsesquioxan block polymers or polytetrafluoroethylene. Thehydrophobic material may in this case be applied by spraying, solutionwetting, sublimation or other suitable methods.

In the simplest case, the mesh is modified by applying a solution of adissolved hydrophobic material with subsequent evaporation of thesolvent, preferably by evaporating an applied polymer solution,preferably a polysilsesquioxan block copolymer solution,polytetrafluoroethylene solution or i-polypropylene solution (Erbil, H.Y., Demirel, A. L., Avcinodot, Y. & Mert, O., Transformation of a SimplePlastic into a Superhydrophobic Surface. Science, 299, No 5611, (2003)1377-80), and particularly preferably a solution ofpoly(methylsilsesquioxan) block poly(methylmethacrylate).

As an alternative, the mesh may also be modified by the covalent bondingof hydrophobic silanes (Nakajima, A., Abe, K., Hashimoto, K. & Watanabe,T., Preparation of hard super-hydrophobic films with visible lighttransmission. Thin Solid Films, 376, No 1-2, (2000) 140-3; Nakajima, A.,Fujishima A., Hashimoto, K. & Watanabe, T., Preparation of TransparentSuperhydrophobic Boehmite and Silica Films by Sublimation of AluminumAcetylacetonate, Advanced Materials, 11, No 16, (1999) 1365); Bico, J.,Marzolin, C. & Quere, D., Pearl drops, Europhys Lett, 47, No 2, (1999)220).

Another way of modifying the mesh is to treat the metal mesh by sprayingon a polymer dispersion, for example a polytetrafluoroethylenedispersion in water, and subsequent sintering at a temperature of about320° C., or a poly(methylsilsesquioxan) block poly(methylmethacrylate)solution in THF and subsequent sintering at a temperature of about 130°C.

The hydrophobicity of the layer may be further increased by increasingthe roughness of the surface, preferably by sandblasting or etching themetal mesh prior to coating, by adding nanoparticles into the coating,or by subsequent plasma treatment of the coating (Morra, M., Occhiello,E. & Garbassi F., Contact angle hysteresis in oxygen plasma treatedpoly(tetrafluoroethylene) Langmuir, 5, No 3, (1989) 872).

After modification, a water contact angle (measured against air)>90°,preferably >120°, particularly preferably >140° is obtained on thelayer.

Another way of achieving the object is to use hydrophobicized ceramicmembranes. In this case, the organic phase likewise passes through themembrane and the electrolyte-containing aqueous phase is retained. Theelectrolytes/salts remain in the water, so that no clogging of thismembrane by salts takes place as occurs in the case of hydrophilicwater-selective membranes. The production of hydrophobicized ceramicmembranes is described, for example, in DE 10 308 110 A1 (U.S.2006/0237361 A1) using fluorosilanes. At the same time, it is feasibleto produce hydrophobic membranes of SiO₂ or Vycor glass. Thehydrophobicized ceramic membranes used may have a pore size of from 0.05to 10 μm, particularly preferably between 0.1 and 5 μm.

Another way of achieving the object is to use hydrophobic polymermembranes of PP, PVDF or PTFE which have sufficient chemical stabilitywith respect to the organic phases respectively employed. In this case,the substantially electrolyte-free organic phase likewise passes throughthe membrane and the electrolyte-containing aqueous phase is retained.Membranes of polypropylene (PP) with a pore size of from 0.05 to 3 μm,particularly preferably from 0.1 to 1 μm, are particularly suitable.

By using the method according to the invention, for example, asubstantially electrolyte-free organic polyether polyol could beseparated from a polyether polyol solution containing a dispersedaqueous phase of electrolyte, i.e. a salt, and water in a singleseparation stage as far as physical solubility of the water in thepolyol being used. The salt-containing aqueous phase, as the dispersephase, can thus be almost entirely separated. At the same time, the salt(K₂SO₄) can be retained up to 99.9%. The salt retention could even beobserved when a polyether almost entirely miscible with water was used.In this case, the phase remaining in the retentate was enriched withsalt.

By using the method according to the invention, for example, asubstantially salt-free organic polycarbonate solution could also beseparated from a polycarbonate solution containing an aqueous phase ofelectrolyte and water, in a single separation stage, to a water contentreaching 0.1% or as far as physical solubility in the separatedpolycarbonate solution. At the same time, the salt (NaCl) could beretained at up to 99.9%, expressed in terms of the initial value of thepolycarbonate solution. The electrolyte-containing aqueous phase, as thedisperse phase, was thus almost entirely separated from the organicphase.

BRIEF DISCUSSION OF THE DRAWINGS

The invention will be explained in more detail below by way of examplewith the aid of FIG. 1, in which:

-   1 is a stirring tank/vessel-   2 is a circulating pump-   3 is a membrane module for the sieve/membrane-   4 is a hydrophobic sieve/membrane-   5 is a valve-   6 is the organic phase (permeate)-   7 is the aqueous phase (retentate)

EXAMPLES

In order to carry out the method according to the invention, a crossflowfiltration cell 3 with a hydrophobic separating means 4 is used. Thesolution to be separated is placed in the stirring tank 1 and pumped ina circuit by a pump 2 through the separating means (membrane/sieve) 4 ata predetermined crossflow rate. An appropriate transmembrane pressuredifference (TMP=(p_(feed)+p_(retentate))/2−p_(permeate)) can be setusing a valve 5 so that the organic solution, which has a lower waterand salt concentration in the permeate 6 than in the retentate 7,permeates through the separating means (membrane/sieve) (i.e. permeate).The electrolyte/salt-containing aqueous and organic phase depleted oforganics (retentate 7) is returned into the stirring tank 1. AKarl-Fischer titration is carried out for analytical determination ofthe water equivalent. The respective electrolyte (salt) concentration isdetermined by titrating the entire base content or by atomic absorptionspectroscopy (AAS). The detection limit for Na is 15 ppb (μg/kg).

Example 1 Production of a Hydrophobicized Sieve

An austenitic steel with the designation 1.4404 is used as the basis forproduction of a superhydrophobic sieve. The absolute filter unit is 5 μm(DTW 4). The metal sieve is cleaned in a 1:1 mixture consisting ofethanol and n-hexane. The surface is subsequently etched with a mixtureof H₂O, H₂O₂ and ammoniacal water at 80° C. After washing with water,coating is carried out with a 5% strength Teflon® dispersion 30-N. Inorder to dry the PTFE dispersion, the sieve is sintered at 320° C. for30 minutes. The water contact angle of a mesh coated in this way is140°±5°. This was found by measuring the so-called static contact angleof an approximately 10 μm large drop of distilled water on the mesh atroom temperature.

Example 2

As described in the general experimental method, a hydrophobic meshproduced according to Example 1 (sieve 06 DTW mesh width 4 to 5 μm,hydrophobicized with 5% of Teflon® N 30) is used in the test apparatusdescribed above. The filtration surface is 0.0044 m². A polyether polyolsolution is employed (trimethylolpropane started polyether with atrifunctionality and an OH number of 45, side chains with 16% ethyleneoxide units and predominantly secondary OH groups). Table 1 shows theresult of the phase separation.

TABLE 1 Tank Crossflow TMP Permeate flux Feed Permeate [° C.] [m/s][bar] [kg/m²hbar] [% H₂O] [% H₂O] 78.7 1.5 0.06 403.4 7.8 5.6 78.7 1.50.06 375.0 8.1 5.7 79.0 1.5 0.07 761.5 8.1 5.6 78.9 1.5 0.18 542.9 8.15.6 79.0 1.5 0.22 458.7 8.2 5.6 79.0 1.5 0.36 265.2 8.1 5.6 79.3 1.50.36 238.9 8.2 5.9 78.7 1.5 0.40 211.9 8.2 5.9

Example 3

As described in the general experimental method, a hydrophobic meshproduced according to Example 1 (sieve 06 DTW mesh width 4 to 5 μm,hydrophobicized with 5% of Teflon N 30) with a PTFE sealing edge moldedin, is used in the test apparatus described above. The filtrationsurface is 0.0044 m². The experiment was conducted similarly as Example2. A polyether polyol solution is employed (product as in Example 2).Table 2 shows the result of the phase separation.

TABLE 2 Permeate Per- Cross- flux Feed meate Feed Tank flow TMP [kg/[ppm [ppm [% Permeate [° C.] [m/s] [bar] m²hbar] KOH] KOH] H₂O] [% H₂O]114.3 1.5 0.3 1246 1826 0.1 4.0 4.0 114.9 1.5 0.5 766 1859 5.8 4.0 3.9115.5 1.5 1.0 464 2194 4.2 4.1 3.8

Example 4

The method is similar to Example 2, but using a ceramic organophilicmembrane. The membrane, a so-called monochannel tube with a tubularchannel, having an internal diameter of 6 mm and a length of 250 mm andan active inner filtration surface of 0.005 m², consists of Al₂O₃ andwas silanized according to the description in patent specification DE 10308 110 A1 (U.S. 2006/0237361 A1). The pore diameter of the membrane is3 μm.

By continuously pumping the feed solution (product as in Example 2) overthe inside of the membrane being used, a clear polyether permeate couldbe drawn off, the water concentration being in the range of physicalsolubility. An increase of the water concentration in the feed couldcorrespondingly be achieved, which corresponds to concentrating theaqueous phase in the circuit.

Table 3 shows the phase separation of the polyether by means of ahydrophobic ceramic membrane with a pore size of 3 μm.

TABLE 3 Tank Crossflow TMP Permeate flux Feed Permeate [° C.] [m/s][bar] [kg/m²hbar] [% H₂O] [% H₂O] 77.0 1.0 0.65 47.1 8.5 5.9 81.0 2.01.36 56.3 8.3 4.8 79.6 3.0 2.11 64.5 8.4 5.2 80.1 3.0 2.15 63.3 8.6 4.780.1 3.0 2.11 56.0 8.8 5.2 80.1 3.0 2.11 49.4 9.1 4.7 80.1 3.0 2.1 47.110.0 4.6 80.1 3.0 2.13 45.7 11.1 4.5 80.1 3.0 2.21 41.5 11.3 4.9

Example 5

A polycarbonate solution (PC molecular weight M_(w) approximately 18,000to 19,000 g/mol), coming from a washing stage in the interface methodfor producing polycarbonate, consisting of polycarbonate,monochlorobenzene, methylene chloride and sodium salts (NaCl) as well asminor amounts of water, neutralized with hydrochloric acid (HCl), wasused in the system described above. The sodium content in the feedsolution was 4.3 ppm (4300 ppb) at the start of the experiment. Thepolycarbonate phase was turbidified by the aqueous emulsion. By usingthe method according to the invention, it was possible to separate asalt-free organic solution by means of an organophilic ceramic membrane.The membrane, a so-called multichannel tube with 7 tubular channels,having an internal channel diameter of 6 mm and a length of 250 mm andan active inner filtration surface of 0.03 m², consists of Al₂O₃ and wassilanized according to the description in patent specification DE 10 308110 A1 (U.S. 2006/0237361 A1). The pore diameter of the membrane is 1μm. The results of the experiment are presented in Table 4, and clearlyshow the reduction of the sodium content of the polycarbonate solution.All permeate samples are clear and have no turbidity to the naked eye.

TABLE 4 Permeate Tank Crossflow TMP flux Permeate [° C.] [m/s] [bar][kg/m²hbar] [ppb Na] 36.8 1.2 2.06 55.8 20 37.5 1.1 2.10 45.9 <15 35.91.1 2.15 28.6 <15

Example 6

A polycarbonate solution coming from a washing stage in the interfacemethod, consisting of polycarbonate, monochlorobenzene, methylenechloride and sodium salts (NaCl) as well as minor amounts of water,neutralized with hydrochloric acid (HCl), was used in the systemdescribed above (FIG. 1). The sodium content in the feed solution was0.8 ppm (800 ppb) at the start of the experiment. The water content wasdetermined as 0.22 wt. % at the start of the experiment. Thepolycarbonate phase was turbidified by the aqueous emulsion. By usingthe method according to the invention, it was possible to separate asalt-free organic solution by means of an organophilic ceramic membraneconsisting of silanized Al₂O₃, as described in Example 3, but with apore size of 0.8 μm. The results of the experiment are presented inTable 5, and clearly show the reduction of the sodium content and watercontent of the polycarbonate solution. All permeate samples are clearand have no turbidity to the naked eye.

TABLE 5 Permeate Tank Crossflow TMP flux Permeate Permeate [° C.] [m/s][bar] [kg/m²hbar] [ppb Na] [% H₂O] 27.9 0.8 2.08 36.9 20 0.09 28.6 0.72.02 31.0 <15 0.08 27.4 0.7 2.08 14.2 <15 0.10

Example 7

A still alkaline polycarbonate solution i.e. containing electrolyte (notneutralized) coming from a washing stage in the interface method,consisting of polycarbonate, monochlorobenzene, methylene chloride andsodium hydroxide as well as minor amounts of water, was used in thesystem described above. The sodium content in the feed solution was 2.9ppm (2900 ppb) at the start of the experiment. The water content wasdetermined as 5.4 wt. % at the start of the experiment. Thepolycarbonate phase was turbidified by the aqueous emulsion. By usingthe method according to the invention, it was possible to separate anelectrolyte-free organic solution by means of an organophilic PP polymermembrane. The PP membrane used is tubular with an internal diameter of5.5 mm and an external diameter of 8.5 mm, a length of 250 mm and anactive inner filtration surface of 0.004 m². The pore diameter of themembrane is 0.2 μm. The results of the experiment are presented in Table6, and clearly show the reduction of the sodium content and watercontent of the separated polycarbonate solution. All permeate samplesare clear and have no turbidity to the naked eye.

TABLE 6 Permeate Tank Crossflow TMP flux Permeate Permeate [° C.] [m/s][bar] [kg/m²hbar] [ppb Na] [% H₂O] 33.3 3.14 0.70 64.0 <15 0.09 33.23.14 0.67 23.3 <15 0.1 33.1 3.14 1.18 8.6 20 0.1 33.1 3.14 1.18 3.8 <150.1

Example 8

THF was distilled over sodium/benzophenone under nitrogen and all of themonomers employed were recondensed under reduced pressure prior topolymerization. CuBr was stirred for 24 h with acetic acid, filteredoff, washed with methanol and dried in vacuo.

Synthesis of pent-4-enyl 2-bromoisobutyrate (1)

160 mmol (13.9 g) penten-4-ol and 50 ml chloroform were introduced intoa flask and cooled to 0° C. 160 mmol (36.8 g) bromoisobutyryl bromide in20 ml chloroform were introduced slowly with cooling and the resultingsolution was stirred for 4 h at room temperature. The reaction solutionwas washed three times with water, dried over MgSO₄ and thenconcentrated by evaporation. The product was distilled in a high vacuum.Boiling point at 3.3×10⁻² mbar: 50° C. Yield: 34.79 g (148 mmol; 92.5%)

¹H NMR (CDCl₃); (ppm)=5.74 (m, 1H); 4.96 (m, 2H); 4.12 (t, 3J=6.6 Hz,2H); 2.10 (m, 2H); 1.87 (s, 6H); 1.72 (quin, 3J=6.3 Hz, 2H)

¹³C NMR (CDCl₃); (ppm)=171.34; 137.05; 115.35; 65.05; 55.66; 30.58;29.73; 27.37. FD mass spectrum: 234.0 (27.8%); 235.0 (100%)

EA (%): calculated: C=45.98; H=6.43; found: C=45.87; H=6.43.

Synthesis of the PMSSQ macroinitiator 5-(trichlosilanyl)-pentyl2-bromoisobutyrate (2)

Methyltrimethoxysilane (MTMS) and (1) in a molar ratio of 20:1 weredissolved in 20 ml THF and 1000 mol % water and 3 mol % HCl were added.The solution was then stirred for 3 h at 0° C., extracted with diethylether and the ether extract was washed with water and dried over MgSO₄.The solvent was evaporated off and the product dried in a high vacuum.¹H NMR (CDCl₃); (ppm)=5.55 (br); 4.14 (br, 2H); 3.44 (s); 1.91 (br, 6H);1.77 (br, 2H); 1.60 (br, 2H); 1.42 (br, 2H); 0.63 (br, 2H); 0.13 (br)

²⁹Si solid state NMR; (ppm)=−48.26 (T1); −57.23 (T2); −65.87 (T3)

Synthesis of poly(methylsilsesquioxan) block poly(methylmethacrylate)(3) by means of atom transfer radical polymerization

The macroinitiator (2) (0.5 g), CuBr and 2,2′-bipyridine in a ratio of1:1:2, and methyl methacrylat (2 g) were degassed three times in 4 mldioxan. The solution was stirred for 8 h at 55° C. and the hybridcopolymer was precipitated with n-heptane and then reprecipitated twicefrom THF in n-heptane and dried in a high vacuum.

¹H NMR (CDCl₃): (ppm)=4.92 (br); 3.57 (br); 1.72 (br); 1.03 (br); 0.15(br).

Coating:

A mesh in the form of a metal mesh of type DTW4 from Haver and Böcker ofa diameter of about 89 mm of austenitic steel labelled 1.4404 is used asthe basic separating means, the absolute filtering unit of which (thenominal pore size) is 5 μm. About 10 ml of a solution of the hybridcopolymer PMSSQ-b-PMMA (3) in THF with a concentration of 2.5 mg/ml isintroduced into a Petri dish and the sieve is immersed horizontally intothe solution for 30 mins, then also washed with THF for about 5 minutesin the Petri dish and then heated for 1 hour at 130° C. in a dryingcabinet as contactlessly as possible. The water contact angle of a sievecoated in this manner is 93°. The advancing contact angle of anapproximately 10 μl large drop of distilled water on the sieve ismeasured at room temperature.

Example 9

This is carried out analogously to Example 2 but using thehydrophobicized mesh from Example 8. A polyether polyol solution is used(the same product as in Example 2). Table 7 shows the results of phaseseparation.

TABLE 7 Permeate Per- Ves- Cross- flux Feed meate Feed sel flow TMP [kg/[ppm [ppm [% Permeate [° C.] [m/s] [bar] m²h] KOH] KOH] H₂O] [% H₂O]88.2 0.9 0.02 61.9 2051 27 8.6 4.1 89.1 0.9 0.04 50.2 n.d.* 28 n.d. 4.289.5 0.91 0.02 85.2 n.d. 27 n.d. 3.9 *not determined

1. Method for separating an organic phase from a mixture of an organicphase comprising an organic solution and an aqueous phase comprising anelectrolyte-containing water, wherein the mixture to be separated ispassed over a hydrophobic porous separating means selected from thegroup consisting of (a) a flat textile structure without hydrophobic ororganophilic coatings or further modification, (b) a flat textilestructure with a hydrophobic coating of a hydrophobic and/ororganophilic material wherein the coating is produced by applying asmooth hydrophobic coating onto a previously roughened surface of theseparating means or by applying a rough hydrophobic coating to thesurface of the separating means, (c) an organophilic membrane having acoating of hydrophobic material, said coating being produced by applyinga rough hydrophobic coating to the surface of the separating means, (d)an organophilic membrane without coating, at least a part of the organicphase of the mixture permeating through the separating means while theelectrolyte-containing aqueous phase is at least partially retainedtogether with the remainder, if any, of the organic phase.
 2. Methodaccording to claim 1, wherein said hydrophobic porous separating meansis a flat textile structure of metal or plastic with a hydrophobiccoating or hydrophobic surface.
 3. Method according to claim 1, whereinsaid flat textile structure is a woven or knitted fabric or a felt ofpolypropylene, polytetraflouoroethylene, polyinylidine fluoride or of acombination of such polymeric materials, without hydrophobic ororganoophilic coatings.
 4. Method according to claim 2 wherein said flattextile structure is a mesh of stainless steel.
 5. Method according toclaim 2, wherein said hydrophobic porous separating means is a wovenmetal mesh with a hydrophobic coating said coating being a coating of ahydrophobic and/or organophilic material.
 6. Method according to claim5, wherein said coating is formed of or by a material selected from thegroup consisting of Teflon® AF PTEF, PTFE dispersion, isocyanates,organic polymers, organic latex, fluoro polymers, fluoro latex, hybridcopolymers, and in particular diblock copolymers of a polysilsesquioxanblock, preferably poly(methylsilsesquioxan) orpoly(stearylsilsesquioxan) and a hydrophobic polymer block selected fromthe series comprising polystyrene, polymethyl acrylate, polyethyl hexylacrylate, polymethyl methacrylate, polydecyl methacrylate, fatty acids,silanes, lacquers, silicones, silicone oils and polysilsesquioxans, ororganic and/or fluoro deposits applied from a plasma process, andmixtures of any two or more thereof.
 7. Method according to claim 1,wherein said separating means is a hydrophobic woven metal mesh withoutfurther surface modification.
 8. Method according to claim 5, whereinthe woven metal mesh has a mesh width <500 μm.
 9. Method according toclaim 8, wherein said mesh width is <5 μm.
 10. Method according to claim1, wherein the mixture to be separated is an emulsion or dispersion of awater-immiscible aromatic or aliphatic organic solvent or polymer andwater and electrolyte.
 11. Method according to claim 1, wherein themixture to be separated is an emulsion or dispersion of polycarbonatedissolved in organic solvent and water and electrolyte.
 12. Methodaccording to claim 1, wherein the mixture to be separated is a mixtureof polyether polyol and water and electrolyte.
 13. Method according toclaim 5, wherein the hydrophobic coating is produced by applying asmooth hydrophobic coating onto a previously roughened surface of theseparating means.
 15. Method according to claim 5, wherein thehydrophobic coating is produced by applying a rough hydrophobic coatingto the surface of the separating means.